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Made available in DSpace on 2014-08-13T14:50:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-08-01Bitstream added on 2014-08-13T18:01:04Z : No. of bitstreams: 1 000740552_20150801.pdf: 754242 bytes, checksum: bc5e88cf87d7787c34d18c1a6e215275 (MD5) Bitstreams deleted on 2015-08-03T12:20:57Z: 000740552_20150801.pdf,. Added 1 bitstream(s) on 2015-08-03T12:22:17Z : No. of bitstreams: 1 000740552.pdf: 1359921 bytes, checksum: 8d035cb78ff5afaa9c1f0d1ef3b02d72 (MD5) / O fator de crescimento dos fibroblastos 8 (FGF8) é expresso pelo oócito bovino, ativa os receptores expressos por células do cumulus e oócitos, e está envolvido na regulação da glicólise e meiose no CCO de murinos. O primeiro objetivo deste estudo foi avaliar os efeitos do FGF8 sobre a expansão das células do cumulus, a progressão da meiose e metabolismo energético em CCOs bovinos submetidos à MIV. Uma vez que foram observadas influências sobre a progressão da meiose e no metabolismo energético, os efeitos de FGF8 sobre a abundância de genes que codificam o RNAm que controlam estes processos foram avaliados. O FGF8 não afetou a expansão do cumulus, mas diminuiu a porcentagem de oócitos que alcançaram a metáfase II, consequentemente houve o aumento da porcentagem de oócitos na metáfase I. Tal efeito foi associado com um efeito inibitório do FGF8 sobre os níveis de RNAm que codifica a Ciclina B1 no oócito. Em contraste com os achados anteriores em murinos, o FGF8 leva à diminuição dos níveis de RNAm de NPR2 nas células do cumulus. O FGF8 tende a diminuir a absorção de glicose e produção de lactato, que foi acompanhada por uma redução significativa nos níveis de RNAm para PFKP em células de cumulus. O FGF8 também tende a diminuir a expressão de RNAm para o LDHA, mas não alterou os níveis de RNAm para GLUT1, GLUT4 e PDHA1 nas células do cumulus, enquanto que aumentou a expressão de RNAm para o PDHA1 no oócito. Este estudo apresenta evidências de que o FGF8 pode retardar a progressão da meiose durante a MIV em bovinos por meio de mecanismos que envolvam redução da expressão de Ciclina B1. Além disso, novamente em contraste com estudos em ratos, os dados sugerem um efeito inibidor modesto de FGF8 sobre o metabolismo glicolítico das células do cumulus durante a maturação in vitro de bovinos / Fibroblast growth factor 8 (FGF8) is expressed by the bovine oocyte, activate receptors expressed by cumulus cells and oocytes, and is involved in the regulation of glycolysis and meiosis in the murine COC. The first aim of this study was to assess the effects of FGF8 on cumulus expansion, meiosis progression and energy metabolism in bovine COCs submitted to IVM. Then, once influences on meiosis progression and energy metabolism were observed, effects of FGF8 on abundance of mRNA encoding genes that control these processes were assessed. FGF8 did not affect cumulus expansion but decreased the percentage of oocytes reaching metaphase II, while increasing the percentage of oocytes in metaphase I. This was associated with an inhibitory effect of FGF8 on levels of mRNA encoding Cyclin B1 in the oocyte. In contrast with previous findings in mice, FGF8 decreased mRNA levels of NPR2 in cumulus cells. FGF8 tended to decrease glucose uptake and lactate production, which was accompanied by a significant reduction in PFKP mRNA abundance in cumulus cells. FGF8 also tended to decrease LDHA mRNA expression, but did not change GLUT1, GLUT4 and PDHA1 mRNA levels in cumulus cells, while it increased PDHA1 mRNA abundance in the oocyte. This study presents novel evidence that FGF8 can slow meiosis progression during IVM in cattle through mechanisms involving reduction of Cyclin B1 expression

Made available in DSpace on 2014-06-11T19:25:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-05-03Bitstream added on 2014-06-13T20:32:58Z : No. of bitstreams: 1 lima_rs_me_botib.pdf: 532125 bytes, checksum: 43ee357752dc07c85fbf032817d7466d (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O estresse térmico materno compromete a fertilidade de vacas leiteiras. Os oócitos nas fases de vesícula germinativa (VG) e maturação são susceptíveis aos efeitos deletérios causados pelo estresse térmico, entretanto os mecanismos celulares desencadeados pela temperatura elevada são pouco conhecidos. Os danos celulares induzidos pelo estresse térmico podem ser manipulados por amplo espectro de fatores biológicos, incluindo o fator de crescimento semelhante à insulina- I (IGF-I). Dessa forma, os objetivos gerais desta proposta foram caracterizar as alterações celulares e de desenvolvimento induzidas pela temperatura elevada em oócitos na fase de VG e avaliar o papel termoprotetor do IGF-I neste contexto. Para tanto, os experimentos 1 e 2 visaram estabelecer o modelo de bloqueio meiótico in vitro. No primeiro experimento foram avaliadas concentrações crescentes (50; 75; 100; 150 e 200 μM) do bloqueador meiótico roscovitina. A porcentagem de oócitos em VG (taxa de bloqueio meiótico) foi baixa em todas as doses de roscovitina testadas. No segundo experimento foram avaliadas diferentes concentrações de butirolactona (0; 12,5; 25; 50 e 100 μM) em meio de inibição meiótica contendo 0 ou 3 mg/ml de albumina sérica bovina (BSA) na porcentagem de oócitos em VG e na porcentagem de oócitos em metáfase II (taxa de reversão do bloqueio meiótico após a maturação in vitro). A eficiência do bloqueio meiótico foi alta para todas as doses de butirolactona avaliadas, exceto 12,5 μM de butirolactona com BSA. De maneira similar, a porcentagem de oócitos em MII foi alta para todos os tratamentos, exceto para dose de 100 μM de butirolactona sem BSA, indicando possível efeito tóxico desta concentração. Com base nestes resultados o modelo de inibição meiótica utilizado para todos os demais experimentos fez uso... / Maternal heat stress compromises fertility of lactating dairy cows. Germinal vesicle stage (GV) and mature oocytes are susceptible to deleterious effects of maternal heat stress. However, the cellular mechanisms triggered by elevated temperature are not well known. The cellular damage induced by heat stress can be manipulated by a wide range of biological factors, such as insulin-like growth factor-I (IGF-I). Therefore, overall objectives of this proposal were to characterize cellular and developmental changes induced by elevated temperature on GV oocytes and evaluate the role of IGF-I in this context. Experiments 1 and 2 aimed to establish an in vitro meiotic arrest model. The first study evaluated the effect of increasing concentrations (50, 75, 100, 150 and 200 μM) of the meiotic inhibitor roscovitine. The percentage of GV oocytes (rate of meiotic arrest) was low at all roscovitine doses tested. In the second experiment different butyrolactoneconcentrations (0, 12.5, 25, 50 and 100 uM) were evaluated in meiotic inhibition medium containing 0 or 3 mg/mL bovine serum albumin (BSA) in percentage of GV oocytes and percentage of metaphase II oocytes (rate of meiotic arrest reversibly after in vitro maturation). Meiotic arrest efficiency was high for all butyrolactone doses tested, except 12.5 μM butyrolactone with BSA. Similarly, the percentage of MII oocytes was high for all doses, except for 100 μM butyrolactone without BSA, indicating a possible toxic effect of this concentration. Based on these results the meiotic arrest model used for all subsequent experiments used 12.5 μM butyrolactone in the absence of BSA. The third experiment evaluated the effect of various IGF-I concentrations (0, 12.5, 25, 50 and 100 ng/ml) on heat-induced DNA fragmentation on GV oocyte. In the absence of IGF-I, heat shock of 41°C for 14 hours increased... (Complete abstract click electronic access below)

Orientador: José Buratini Júnior / Banca: Fabíola Freitas de Paula-Lopes / Banca: fernanda da Cruz Landim / Resumo: O fator de crescimento dos fibroblastos 8 (FGF8) é expresso pelo oócito bovino, ativa os receptores expressos por células do cumulus e oócitos, e está envolvido na regulação da glicólise e meiose no CCO de murinos. O primeiro objetivo deste estudo foi avaliar os efeitos do FGF8 sobre a expansão das células do cumulus, a progressão da meiose e metabolismo energético em CCOs bovinos submetidos à MIV. Uma vez que foram observadas influências sobre a progressão da meiose e no metabolismo energético, os efeitos de FGF8 sobre a abundância de genes que codificam o RNAm que controlam estes processos foram avaliados. O FGF8 não afetou a expansão do cumulus, mas diminuiu a porcentagem de oócitos que alcançaram a metáfase II, consequentemente houve o aumento da porcentagem de oócitos na metáfase I. Tal efeito foi associado com um efeito inibitório do FGF8 sobre os níveis de RNAm que codifica a Ciclina B1 no oócito. Em contraste com os achados anteriores em murinos, o FGF8 leva à diminuição dos níveis de RNAm de NPR2 nas células do cumulus. O FGF8 tende a diminuir a absorção de glicose e produção de lactato, que foi acompanhada por uma redução significativa nos níveis de RNAm para PFKP em células de cumulus. O FGF8 também tende a diminuir a expressão de RNAm para o LDHA, mas não alterou os níveis de RNAm para GLUT1, GLUT4 e PDHA1 nas células do cumulus, enquanto que aumentou a expressão de RNAm para o PDHA1 no oócito. Este estudo apresenta evidências de que o FGF8 pode retardar a progressão da meiose durante a MIV em bovinos por meio de mecanismos que envolvam redução da expressão de Ciclina B1. Além disso, novamente em contraste com estudos em ratos, os dados sugerem um efeito inibidor modesto de FGF8 sobre o metabolismo glicolítico das células do cumulus durante a maturação in vitro de bovinos / Abstract: Fibroblast growth factor 8 (FGF8) is expressed by the bovine oocyte, activate receptors expressed by cumulus cells and oocytes, and is involved in the regulation of glycolysis and meiosis in the murine COC. The first aim of this study was to assess the effects of FGF8 on cumulus expansion, meiosis progression and energy metabolism in bovine COCs submitted to IVM. Then, once influences on meiosis progression and energy metabolism were observed, effects of FGF8 on abundance of mRNA encoding genes that control these processes were assessed. FGF8 did not affect cumulus expansion but decreased the percentage of oocytes reaching metaphase II, while increasing the percentage of oocytes in metaphase I. This was associated with an inhibitory effect of FGF8 on levels of mRNA encoding Cyclin B1 in the oocyte. In contrast with previous findings in mice, FGF8 decreased mRNA levels of NPR2 in cumulus cells. FGF8 tended to decrease glucose uptake and lactate production, which was accompanied by a significant reduction in PFKP mRNA abundance in cumulus cells. FGF8 also tended to decrease LDHA mRNA expression, but did not change GLUT1, GLUT4 and PDHA1 mRNA levels in cumulus cells, while it increased PDHA1 mRNA abundance in the oocyte. This study presents novel evidence that FGF8 can slow meiosis progression during IVM in cattle through mechanisms involving reduction of Cyclin B1 expression / Doutor

Orientador: Fabíola Freitas de Paula Lopes / Banca: Ciro Moraes Barros / Banca: José Antônio Visintin / Resumo: O estresse térmico materno compromete a fertilidade de vacas leiteiras. Os oócitos nas fases de vesícula germinativa (VG) e maturação são susceptíveis aos efeitos deletérios causados pelo estresse térmico, entretanto os mecanismos celulares desencadeados pela temperatura elevada são pouco conhecidos. Os danos celulares induzidos pelo estresse térmico podem ser manipulados por amplo espectro de fatores biológicos, incluindo o fator de crescimento semelhante à insulina- I (IGF-I). Dessa forma, os objetivos gerais desta proposta foram caracterizar as alterações celulares e de desenvolvimento induzidas pela temperatura elevada em oócitos na fase de VG e avaliar o papel termoprotetor do IGF-I neste contexto. Para tanto, os experimentos 1 e 2 visaram estabelecer o modelo de bloqueio meiótico in vitro. No primeiro experimento foram avaliadas concentrações crescentes (50; 75; 100; 150 e 200 μM) do bloqueador meiótico roscovitina. A porcentagem de oócitos em VG (taxa de bloqueio meiótico) foi baixa em todas as doses de roscovitina testadas. No segundo experimento foram avaliadas diferentes concentrações de butirolactona (0; 12,5; 25; 50 e 100 μM) em meio de inibição meiótica contendo 0 ou 3 mg/ml de albumina sérica bovina (BSA) na porcentagem de oócitos em VG e na porcentagem de oócitos em metáfase II (taxa de reversão do bloqueio meiótico após a maturação in vitro). A eficiência do bloqueio meiótico foi alta para todas as doses de butirolactona avaliadas, exceto 12,5 μM de butirolactona com BSA. De maneira similar, a porcentagem de oócitos em MII foi alta para todos os tratamentos, exceto para dose de 100 μM de butirolactona sem BSA, indicando possível efeito tóxico desta concentração. Com base nestes resultados o modelo de inibição meiótica utilizado para todos os demais experimentos fez uso... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Maternal heat stress compromises fertility of lactating dairy cows. Germinal vesicle stage (GV) and mature oocytes are susceptible to deleterious effects of maternal heat stress. However, the cellular mechanisms triggered by elevated temperature are not well known. The cellular damage induced by heat stress can be manipulated by a wide range of biological factors, such as insulin-like growth factor-I (IGF-I). Therefore, overall objectives of this proposal were to characterize cellular and developmental changes induced by elevated temperature on GV oocytes and evaluate the role of IGF-I in this context. Experiments 1 and 2 aimed to establish an in vitro meiotic arrest model. The first study evaluated the effect of increasing concentrations (50, 75, 100, 150 and 200 μM) of the meiotic inhibitor roscovitine. The percentage of GV oocytes (rate of meiotic arrest) was low at all roscovitine doses tested. In the second experiment different butyrolactoneconcentrations (0, 12.5, 25, 50 and 100 uM) were evaluated in meiotic inhibition medium containing 0 or 3 mg/mL bovine serum albumin (BSA) in percentage of GV oocytes and percentage of metaphase II oocytes (rate of meiotic arrest reversibly after in vitro maturation). Meiotic arrest efficiency was high for all butyrolactone doses tested, except 12.5 μM butyrolactone with BSA. Similarly, the percentage of MII oocytes was high for all doses, except for 100 μM butyrolactone without BSA, indicating a possible toxic effect of this concentration. Based on these results the meiotic arrest model used for all subsequent experiments used 12.5 μM butyrolactone in the absence of BSA. The third experiment evaluated the effect of various IGF-I concentrations (0, 12.5, 25, 50 and 100 ng/ml) on heat-induced DNA fragmentation on GV oocyte. In the absence of IGF-I, heat shock of 41°C for 14 hours increased... (Complete abstract click electronic access below) / Mestre

No description available.

Bovine morulae (day 6; n=328) were obtained to evaluate the effect of uterine flushings (UF) obtained from ovariectomized progesterone (P) or estrogen (E) treated cows or from previously superovulated cows on day 6, 10, or 15 post insemination on early embryo development. Ninety-eight cows were superovulated with follicle stimulating hormone. Embryos were collected by non-surgical flushing procedures and morphologically evaluated and randomly assigned to culture. Embryos were cultured in Ham's F-10 containing 10% steer serum (SS), 10% P or E concentrated UF, 10% SS plus 1% UF from day 6, 10, or 15, or different concentrations of UF from day 6, 10, or 15 (10%, 1%, .1%, .01%). Embryos were cultured up to the hatched blastocyst stage or degeneration and evaluated at 12 h intervals. Treatment differences were evaluated by analysis of variance after assigning a value of 0 to 5 to each embryo representing its final stage of development. Overall analysis revealed that embryo development was significantly affected by supplement, but not affected by initial quality. Final developmental score was significantly higher in SS than in all other supplements. Combination of 1% UF and 10% SS resulted in enhanced embryo development compared to all single UF protein treatments. Time to the hatching blastocyst and hatched blastocyst developmental stages was reduced (P<.05) in 1% day 15 UF compared to 1% day 6 and day 10 UF plus 10% SS, or 10% SS. These results suggest that day 15 UF may contain a substance which may shorten the time of embryo hatching in vitro. / Master of Science

Three dam types (straightbred (SB), single cross (2x), three-breed cross (3xX)), located in three Virginia herds (Bland, Hanover, State Farm) were bred to a combination of Angus, Limousin x Shorthorn and Maine Anjou x Shorthorn bulls. Over four calf crop years, 1978-1981, 1040 matings were recorded. Reproductive performance of the dam, calf livability, average daily gain, weaning conformation and condition scores, adjusted 205-day weight, actual weaning weight and total damn productivity (kg. calf weaned/cow exposed) were assessed with regard to dam type, as well as individual dam breed effects. Three-breed cross cows were evaluated for both maternal sire and grandsire effects. Pregnancy rates were similar among the three cow types, but 3X dams produced the highest weaning rates, due to lower death losses. Weaning weights of 2X and 3X progeny were comparable. Straightbred dams were the least productive, weaning slower-gaining, lighter-weight calves. Three-breed cross dams weaned an additional 30 and 17 kg. over SB and 2X cows, respectively. Dam breed effects were significant among SB, 2X and 3X maternal sires. State Farm was the most productive location and Angus sires out-produced the two larger-framed bull types. Results of this experiment indicate that among the three dam types, maternal efficiency was maximized within the 3X cow. Use of a larger type sire breed was not necessarily indicative of escalated weaning weights and improved dam productivity. An increase in dam reproductive ability and a decrease in calf mortality may prove more advantageous than striving for increased growth in crossbreeding programs. / M. S.